Hydraulically controlled dial



1957 R. L. HUFFMAN HYDRAULICALLY CONTROLLED DIAL Filed ma 26, 1953 H l 4 1 W INVENTOR. ROBERT' L. HUFFMAN AT TY Unite States Patent HYBRAULICALLY coNTRoLLED DIAL Robert L. Hufiman, Palatine, Ill., assignor to General Telephone Laboratories, Incorporated, a corporation of Deiaware Application May 26, 1953, Serial No. 357,516

Claims. (Cl. 179-90) The present invention relates in general to impulse senders and more particularly to calling devices for automatic telephone systems or signalling systems.

An object of the invention is the production of a device of this character in which the speed governing means is solely controlled by hydraulic means and thereby to improve the mechanical controlling mechanism of automatic telephone dials.

A further object of the invention is to produce an improved device of this character that may be free from excessive wear, stickiness and speed variation due to the low temperature sometimes experienced by such dials.

A still further object of the invention is to reduce the cost of production and yet to provide an improved device which is a more simplified and compact form and which is less prone to get out of adjustment under normal operating conditions.

These and other objects are accomplished in accordance with this invention by eliminating the worm and fly ball governor and the restoring spring as normally used for currently manufactured dials, and replacing them with two hydraulically controlled resilient metallic bellows and interconnecting means which are arranged in such a manner that the bellows are freely operated to store energy when the finger plate is manually rotated and also arranged in a manner so that the restoring operation of the bellows is retarded with a view to governing the speed of impulse transmission when the finger plate is released. The invention, both as to its organization and method of operation together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawing in which the'single figure is shown as a rear view of a calling device embodying the present invention.

Referring now more particularly to the drawing, a calliug device comprises a finger plate (not shown), a casing 11, an impulse cam 12 and a pinion 13 connected to the finger plate, and a rack 14 which is secured to the metallic bellows 15 and in mesh with the gears of pinion 13. Metallic bellows 15 is connected by tubing 17 to a check valve 18 which is connected to metallic bellows 2% by a tubing 19.

The bellows 15 and 20 are made from resilient metal and only one communicating channel is provided for each bellows. The bellows are capable of expansion and compression from their normal form to store energy when force is applied thereto. When such force is no longer applied the energy stored in the resilient metal by the expansion or compression of the bellows is effective to restore the bellows to their normal form. A low viscosity index liquid, which retains its free flowing characteristics in varying degrees of temperature, is included in the metallic bellows, tubings and check valve. A ball 22 in check valve 18 is normally held in valve seat 24 by the flexible spring 21. A small groove 23, or orifice, is provided in the valve seat 24 to govern the return flow of the liquid. If desired a needle valve (not shown) could be provided ice in a well known manner to vary the return flow of the liquid through the groove or orifice 23 in order to further regulate the return flow of the liquid.

The outer periphery of impulse cam 12 is provided with a plurality of spaced impulse cam lobes 25 for operating the impulse springs 26 on the return movement of the finger plate and impulse cam 12. One of the impulse springs 26 is provided with bent-over ears and a pivot point 32 is provided in these ears for pivotally mounting an L-shaped impulse lever 27. The flat surface of this lever impulse spring engages the lower arm portion of the lever 27 which corresponds to the lower horizontal leg of the letter L. A light restoring spring 28 is provided on this lever impulse spring for restoring the lever 27 to the position shown in the drawing. The pivotal construction of the lever impulse spring and its lever 27 permits rotation of lever 27 about its pivot 32 without separating the impulse springs when the impulse cam 12 is manually rotated counter-clockwise and the impulse cam lobes 25 successively engage and rotate lever 27. However, when the impulse cam 12 is restored in the opposite direction the impulse carn lobes 25 on their return movement successively engage lever 27 and cause the lever impulse spring to move and disengage itself from its cooperating impulse spring to thereby transmit an impulse for each separation of said impulse springs.

An oil-normal cam 31 is provided on another portion of the periphery of impulse cam 12 for operating the shunt springs 29 when the finger plate and impulse cam 12 have been moved from normal. The shunt springs 29 comprise three normally separated springs also mounted on the casing. A bushing 30 provided on the outer shunt spring normally engages the oil-normal cam 31 to maintain the three shunt springs separated. When the impulse cam 12 is moved off-normal, cam 31 moves away from bushing 31 thereby causing the three shunt springs to engage each other.

Having described the structural details of the improved calling device its operation will now be described. When the finger plate is manually rotated in a clockwise direction as seen from the front, the impulse cam 12, as viewed from the rear of the calling device, is rotated in a counter-clockwise direction. Shunt springs 29 close as soon as oflF-normal cam 31 moves away from bushing 39. The impulse cam lobes 25 rotate the lever 27 on its pivot 32 without separating the impulse springs 26 during this manual rotation. The pinion 13 is rotated with the finger plate and impulse cam 12 and since the pinion 13 is in mesh with the rack 14 the rack is moved longitudinally to compress the bellows 15 to store energy. The compression of bellows 15 forces the liquid therein through tubing 17 and causes the ball 22 to move from its valve seat 24 so as not to restrict the flow of the liquid through the check valve 18 and through the tubing 19 into bellows 20 which thereby expanded to store energy.

When the finger is removed from the finger plate the tension or energy stored up in the resilient metallic bellows 20 and 15 causes a reversal of flow of the liquid in the bellows, check valve and tubings. In check valve 18 spring 21 now causes ball 22 to be seated in valve seat 24 thereby restricting the flow of liquid through only the groove or orifice 23 to thereby retard the flow of liquid in order to govern the return movement of bellows 15 and 2%. As the bellows 15 gradually returns to its normal form the rack 14 is moved in its other direction to rotate pinion 13 in a clockwise direction as viewed in the drawing. Both the finger plate and impulse cam 12 are rotated back to normal with the pinion 13.

The return rotation of the impulse cam 12 causes the impulse cam lobes 25 to successively engage lever 27 to separate the impulse springs 26 to transmit the desired impulses. The speed of the return rotation of the impulse cam 12 and the speed of impulse transmission is,

governed by the retarded flow of the liquid through the groove orrorifice 23. In case a certaintsuitable liquid is alwaysrnsed the orificemeed only be large-enough toj give'the' desired speed :of' impulse itransmissrom" How-i movement and a restoring movement, a conveying means interconnecting said members, liquid means 1n said resilient members and said conveying means,'retard1ng means associated with said conveying means for retarding only the restoring movement of said resilient members, and means including impulse contacts operated by the restoring movement of said members.

4. In a telephone dial, a cam, a pinion secured to said cam, means for manually moving said cam to rotate said pinion, a rack meshing with said pinion and moved by the rotation of said pinion, a first bellows having resilient characteristics, said first bellows secured to said rack and being compressed by the movement of said rack ing means connected to said bellows, alow viscosity index liquid in said bellows and conveying means, a rack conected withlsaid bellows, a pinion on said cam con nected in mesh with said rack, means for manually rotating said cam and pinion to operate said rack to compress said bellows, the compression of said bellows forcing said liquid through saidconveying means, the Com",

pression of said bellows tensioning said bellows against saidrack, said tension stored in said bellows effective responsive to the release of said manually operable means for restoring said rack, said pinion, said cam and said manually operable means tobnormal, retarding means associated with said conveying means for retarding the return flow of said liquid into the said bellows to thereby govern the speed under which said cam restores to its normalposition, and impulse springs operated during the restoration of said cam.

2. In a telephone dial, a first resilient means, a second 1 a pressing said first bellows to cause the liquid contained resilient means, conveying means interconnecting said first and second resilient means, hydraulic liquid in said first, second, and conveying means, manually operable means, means for compressing said first resilient means responsive to the operation 'of said manually operable means from normal, means including said conveying means for expanding said second resilient means in response to the compression of said first resilient means, the compression of said first resilient means and the exto store energy, a second bellows having resilient characteristics, conveying means interconnecting said first and second bellows, a low viscosity index liquid in said bellows and said conveying means, the compression of said 7 first bellowscausing said'liquid to freely flow through conveying means effective to retard the return flow of said liquid for controlling the speed under Whichsaid first pansion of said second resilient means effective when said manually operable means is released for restoring said manually operable means to normal, retarding means associated with said conveying means for retarding the return of both said resilient means to thereby retard the return movement of said manually operable means, and

impulsing springs controlled by the return movement of said manually movable means.

3. In a hydraulically controlled impulse dial comprising a pair of resilient members each having an operating said conveying means to said second bellows to expand said second bellows to store energy, the stored energy in said bellows effective when said manually movable means is released to restore said rack to rotate said pinion and said cam, a check valve in said conveying means for restricting the return flow of saidliquid to retard the return movement of said bellows therebyretarding the return movement of said rack, pinion and cam, and impulsing springs controlled by the return movement of said cam.

5. In a dial, a cam with impulse lobes, a first and a second bellows, conveying means interconnecting the two bellows, a low viscosity index liquid in said bellows and conveying means, means for manually moving said cam, means interconnecting said cam and said first bellows responsive to said manual movement of said cam for comtherein to freely flow through said conveyingmeans to expand said second bellows, a retarding means in said and second bellows restore after release of said manual means, said interconnecting means controlled by said retarded restoring of said bellows to govern the restoring speed of said cam, and impulse contacts operated by the impulse lobes in said cam'during restoring movement of said cam. a V a 7 References Cited in the file of this patent UNITED STATES PATENTS r 2,377,461 Swift June 5, 1945 2,436,785 Bergier et al, -2 Mar. 2, 1948 2,440,314 Turner Apr. 27, 1948 2,522,984 Boisseau et a1. Sept.'19, 1950 2,589,160

Swartz Mar. 11, 1952 

